Apparatus for the variable setting of the control times of gas exchange valves of an internal combustion engine

ABSTRACT

The invention relates to an apparatus ( 1 ) for the variable setting of the control times of gas exchange valves of an internal combustion engine, having a stator ( 2 ) and an output element ( 3 ) which is arranged coaxially with respect to the former, the two components being mounted such that they can rotate with respect to one another, and having a housing ( 11 ) which is configured separately with respect to the stator ( 2 ) and with respect to the output element ( 3 ) and which surrounds the stator ( 2 ) and the output element ( 3 ) at least partly and prevents engine oil escaping from the apparatus ( 1 ), an outer circumferential surface of the stator ( 2 ) being configured in the circumferential direction with a radial profile, into which the housing ( 11 ) protrudes in such a way that a form-fitting connection of both components is produced in the circumferential direction.

FIELD OF THE INVENTION

The invention relates to an apparatus for the variable setting of thecontrol times of gas exchange valves of an internal combustion engine,having a stator and an output element which is arranged coaxially withrespect to the former, the two components being mounted such that theycan rotate with respect to one another, and having a housing which isconfigured separately with respect to the stator and with respect to theoutput element and which surrounds the stator and the output element atleast partly.

In internal combustion engines, camshafts are used to actuate the gasexchange valves. Camshafts are attached in the internal combustionengine in such a way that cams which are attached to them bear againstcam followers, for example cup tappets, drag levers or valve rockers. Ifa camshaft is set in rotation, the cams roll on the cam followers whichin turn actuate the gas exchange valves. Both the opening duration andthe opening amplitude, and also the opening and closing times of the gasexchange valves, are therefore fixed by the position and the shape ofthe cams.

Modern engine concepts tend to design the valve timing mechanism in avariable manner. Firstly, the valve stroke and the valve openingduration are to be designed to be variable, extending as far as thecomplete switching-off of individual cylinders. For this purpose,concepts are provided such as switchable cam followers orelectrohydraulic or electric valve actuating systems. Furthermore, ithas proven advantageous to be able to influence the opening and closingtimes of the gas exchange valves during operation of the internalcombustion engine. Here, it is particularly desirable to be able toinfluence the opening and closing times of the inlet and the outletvalves separately, in order, for example, to set a defined valve overlapin a targeted manner. As a result of the setting of the opening andclosing times of the gas exchange valves as a function of the currentrange of the characteristic diagram of the engine, for example as afunction of the current rotational speed or the current load, thespecific fuel consumption can be reduced, the exhaust-gas behaviour canbe influenced positively, and the engine efficiency, the maximum torqueand the maximum power output can be increased.

The above-described variability of the valve control times is achievedby a relative change in the phase position of the camshaft with respectto the crankshaft. Here, the camshaft is usually drive-connected to thecrankshaft via a chain drive, belt drive, gearwheel drive, or driveconcepts which function in an identical manner. An apparatus forchanging the control times of an internal combustion engine, also calleda camshaft adjuster in the following text, is attached between the chaindrive, belt drive or gearwheel drive which is driven by the crankshaftand the camshaft, which apparatus transmits the torque from thecrankshaft to the camshaft. Here, this apparatus is configured in such away that, during operation of the internal combustion engine, the phaseposition between the crankshaft and the camshaft is maintained reliablyand, if desired, the camshaft can be rotated in a defined angular rangewith respect to the crankshaft.

Belt-driven camshaft adjusters are usually arranged outside the cylinderhead. It is to be noted here that the camshaft adjuster must be sealedoff completely with respect to the surroundings, in order to preventleakage of engine oil into the engine compartment. Any leakage oil whichoccurs must be collected and led back into the cylinder head.

In internal combustion engines having in each case one camshaft for theinlet valves and one camshaft for the outlet valves, the said camshaftscan be equipped with in each case one camshaft adjuster. As a result,the opening and closing times of the inlet and outlet valves can beshifted temporally relative to one another and the valve overlaps can beset in a targeted manner.

Modern camshaft adjusters are usually seated at the drive-side end ofthe camshaft. However, the camshaft adjuster can also be arranged on anintermediate shaft, a non-rotating component or the crankshaft. The saidcamshaft adjuster comprises a drive wheel which is driven by thecrankshaft and maintains a fixed phase relationship with respect to thelatter, an output part which is drive-connected to the camshaft and anadjusting mechanism which transmits the torque from the drive wheel tothe output part. In the case of a camshaft adjuster which is notarranged on the crankshaft, the drive wheel can be configured as a chainsprocket, a belt pulley or a gearwheel and is driven by the crankshaftby means of a chain drive, a belt drive or a gearwheel drive. Theadjusting mechanism can be operated electrically (by means of a driventhree-shafted gear mechanism), hydraulically or pneumatically.

One preferred embodiment of hydraulic camshaft adjusters is what isknown as the rotary piston adjuster. In the latter, the drive wheel isconnected fixedly in terms of rotation to a stator. The stator and anoutput element are arranged concentrically with respect to one another,the output element being connected to a camshaft, an extension of thecamshaft or an intermediate shaft with a force-transmitting,form-fitting or material-to-material connection, for example by means ofa press fit, a screw connection or welded connection. A plurality ofhollow spaces which are spaced apart in the circumferential directionand extend radially outwards starting from the output element are formedin the stator. The hollow spaces are delimited in a pressure-tightmanner in the axial direction by side covers. A vane which is connectedto the output element and divides every hollow space into two pressurechambers extends into each of these hollow spaces. The phase of thecamshaft relative to the crankshaft can be set or maintained by targetedconnection of the individual pressure chambers to a pressure-medium pumpor to a tank.

In order to control the camshaft adjuster, sensors detect thecharacteristic data of the engine, such as the load state and therotational speed. This data is fed to an electronic control unit which,after comparison of the data with an engine data map of the internalcombustion engine, controls the inflow and the outflow of pressuremedium to and from the different pressure chambers.

In order to adjust the phase position of the camshaft with respect tothe crankshaft, in hydraulic camshaft adjusters one of the two pressurechambers, which act against one another, of a hollow space is connectedto a pressure-medium pump and the other is connected to the tank. As aresult, the vane is displaced and the camshaft is therefore rotateddirectly with respect to the crankshaft by the application of pressureto one chamber and by the pressure relief of the other chamber. In orderto maintain the phase position, both pressure chambers are eitherconnected to the pressure-medium pump or are disconnected both from thepressure-medium pump and from the tank.

The pressure-medium flows to and from the pressure chambers arecontrolled by means of a control valve, usually a 4/3-way proportionalvalve. A valve housing is provided with in each case one connection forthe pressure chambers (working connection), one connection to thepressure-medium pump and at least one connection to a tank. An axiallydisplaceable control piston is arranged within the valve housing whichis of substantially hollow-cylindrical configuration. The control pistoncan be moved axially into every position between two defined endpositions by means of an electromagnetic actuator counter to the springforce of a spring element. Furthermore, the control piston is providedwith annular grooves and control edges, as a result of which theindividual pressure chambers can be connected optionally to thepressure-medium pump or the tank. A position of the control piston canlikewise be provided, in which position the pressure chambers aredisconnected both from the pressure-medium pump and also from thepressure-medium tank.

DE 199 08 934 A1 has disclosed an apparatus of this type. Here, it is anapparatus of the rotary piston construction type. A stator is mountedrotatably on an output element which is connected fixedly in terms ofrotation to a camshaft. The stator is configured with recesses which areopen towards the output element. Compensation washers are provided inthe axial direction of the apparatus, which compensation washers delimitthe recesses in the axial direction in a sealing manner. The recessesare closed in a pressure-tight manner by the stator, the output elementand the compensation washers and therefore form pressure spaces. Vaneswhich extend into the recesses are formed on the outer circumferentialface of the output element. The vanes are configured in such a way thatthey divide the pressure spaces into in each case two pressure chamberswhich act against one another. The phase position of the output elementwith respect to the stator and therefore of the camshaft with respect tothe crankshaft can be maintained or adjusted optionally by introducingor discharging pressure medium to or from the pressure chambers. Forthis purpose, a device is provided for supplying pressure medium havingpressure-medium lines and a control valve.

The stator, the output element and the compensation washers areencapsulated by a two-part housing which is connected fixedly in termsof rotation to a drive wheel which is configured as a toothed beltpulley by means of fastening means.

The flat bases of the housing halves ensure pressure-tight contact ofthe compensation washers with the stator and the output element.

Furthermore, the drive torque of the crankshaft is transmitted with afriction fit to the stator via the drive wheel and the bases of thecompensation washers. As an alternative, it is proposed that the sidefaces of the stator have a profile, as a result of which an additionalform-fitting connection can be attained.

In this embodiment, a large number of components are required to realizethe apparatus, as a result of which increased assembly expenditure andtherefore manufacturing costs occur. Furthermore, the above-describedtransmission of the torque from the drive wheel to the stator involvesincreased manufacturing expenditure which has a negative effect on thecosts of the apparatus.

SUMMARY OF THE INVENTION

The invention is therefore based on the object of avoiding thesedescribed disadvantages and therefore of proposing an apparatus for thevariable setting of the control times of gas exchange valves of aninternal combustion engine, in which the number of components andtherefore the assembly complexity and the manufacturing costs of theapparatus are reduced. Furthermore, the apparatus is to be improved insuch a way that the transmission of the torque of the crankshaft to thestator is improved and is achieved with less expensive measures.

According to the invention, the object is achieved in that an outercircumferential surface of the stator is configured in thecircumferential direction with a radial profile, into which the housingprotrudes in such a way that a form-fitting connection of bothcomponents is produced in the circumferential direction.

Apparatuses of this type can be provided with a chain sprocket, a beltpulley or a gearwheel and can be drive-connected to the crankshaft via achain drive, a toothed-belt drive or a gearwheel drive.

If the apparatus is to be driven by means of a toothed belt, the housingis to be configured in such a way that it prevents pressure-mediumescaping from the apparatus.

Here, there can be provision for at least one pressure space to beformed between the stator and the output element, the housing tocomprise at least two housing elements, and at least one flat section ofthe housing which stands perpendicularly with respect to the axialdirection of the apparatus to act as a sealing face for the pressurespace in the axial direction.

In developments of the invention, the stator and/or at least one of thehousing elements can be configured as a sheet-metal part which is formedwithout cutting. As an alternative, the stator can be of solidconfiguration, for example as a sintered component.

If the stator and/or the at least one housing element are configured asa sheet-metal part which is formed without cutting, these components canbe manufactured by a deep-drawing process.

The two housing elements can be connected to one another by means of awelded connection, as a result of which the housing prevents pressuremedium escaping from the apparatus.

In one advantageous development of the invention, there can be provisionfor a cylindrical section which extends in the axial direction to beformed on the housing for sealing off the apparatus with respect to aradial shaft sealing ring. In addition, there can be provision for acamshaft to engage into the section, and for a gap to be formed betweenthe internal diameter of the section and the camshaft. As a result, theapparatus can be arranged outside the cylinder head, the sectionengaging into an opening of the cylinder head and being sealed off withrespect to the latter by means of the radial shaft seal. Leakage oilwhich occurs can be guided back into the cylinder head and thereforeinto the crankcase via the gap between the section and the camshaft.

In a further advantageous development of the invention, there isprovision for shaped elements to be formed on at least one of thehousing elements in order to increase the surface area. These shapedelements serve firstly to reinforce the housing, and secondly toincrease its surface area, which leads to improved cooling of theapparatus. The shaped elements can be configured, for example, ascooling fins.

The following two objects, inter alia, are achieved by the encapsulationof the stator and the output element by way of a housing. Firstly, thehousing serves to close the pressure spaces in the axial direction ofthe apparatus in a pressure-tight manner. This can take place eitherindirectly, by pressing sealing washers against the stator, or directly,by the formation of sealing faces on the housing. In the case ofapparatuses which are driven by toothed belts and are usually arrangedoutside the cylinder head, the housing additionally serves as anencapsulation of the apparatus which prevents pressure medium escapingfrom the apparatus into the engine compartment. Any leakage oil whichoccurs is collected within the housing and guided back into the enginecompartment via an axial section. The output element is usuallyconfigured as a sintered component in these embodiments, which sinteredcomponent has to be sealed in a work step which follows the shapingprocess. This work step is usually very time-intensive and thereforecost-intensive.

Sealing work steps of this type can be dispensed with by theconfiguration of the housing as a sheet-metal part which is formedwithout cutting and is inherently oil-tight. Furthermore, the number ofconnecting points to be sealed will be reduced from at least two(between the side covers and the stator) to one (between the housinghalves).

In comparison with the apparatus which is described in the prior art, acost advantage can be achieved by the fact that at least the function ofone of the sealing washers is integrated into the housing. To this end,at least one base of a section of the housing of cup-shapedconfiguration is configured to be flat. This base bears in apressure-tight manner both against the stator and against the outputelement in the axial direction.

The housing comprises two housing elements, into which the stator andthe output element can be placed. Here, both housing elements can be ofcup-shaped configuration. An embodiment with a cup-shaped housingelement and a flat housing element is likewise conceivable. The housingelements can be connected to one another by means of connecting means,such as screws or bolts, or with a force-fitting or material-to-materialfit. The base of at least one of the cup-shaped sections is flat andconfigured in such a way that it delimits the pressure spaces which areformed between the stator and the output element in a pressure-tightmanner in an axial direction. It is likewise conceivable that thepressure spaces are delimited in both axial directions by flat sectionsof the housing which stand perpendicularly with respect to the axialdirection of the apparatus.

The costs of the apparatus can be reduced considerably by the reductionin the number of components and the associated lower assemblyexpenditure. Here, the inexpensive manufacture of the housing elementsby way of a forming process without cutting, for example a deep-drawingprocess, likewise has a positive effect.

The use of a stator which is manufactured from a sheet-metal blank in aforming process without cutting is likewise conceivable. A radialprofile is formed in the circumferential direction of the stator by theconfiguration of the stator as a thin-walled shaped sheet-metal part. Inthis case, the stator comprises radially outer circumferential walls,radially inner circumferential walls and side walls which in each caseconnect an inner circumferential wall to an outer circumferential wall.This profile can be used to transmit the torque, which is transmittedfrom the drive wheel to the housing, to the stator. To this end, theinternal diameter of the circumferential surface of the cup-shapedsection or sections is adapted to the external diameter of the outercircumferential walls. As a consequence, the stator can be accommodatedin the housing, the said stator being centred at the same time relativeto the housing. Formed recesses are provided between the outercircumferential walls of the stator on the cup-shaped section orsections of the housing element or housing elements, which formedrecesses are configured in such a way that they bear against therespective side walls. As a result, a form-fitting connection isproduced in the circumferential direction, via which the torque can betransmitted from the housing to the stator. The stator can bemanufactured so as to be thinner and therefore lighter and lessexpensive as a result of the transmission of the torque by means ofsurfaces which are in contact in the circumferential direction and theincreased contact surface area. Moreover, this type of connection can bemanufactured considerably more reliably.

Furthermore, the formed recesses in the housing can be used for theengagement of the drive wheel. A connection which is form-fitting in thecircumferential direction can also be produced at this point by theshaping of an internal circumferential surface of the drive wheel whichis complementary to the external circumferential surface of the housing.

The use of this form-fitting connection between the housing and a statorof solid configuration, for example made from sintered metal, islikewise conceivable. For this purpose, the profile of the externalcircumferential surface of the stator is advantageously taken intoconsideration as early as in the shaping die. As a result, no additionalcosts are produced, whereas the quality of the connection between thestator and the housing can be improved considerably.

The invention is of course also conceivable in apparatuses which aredriven by chain sprockets or gearwheels.

In one advantageous development of the invention, a locking device isprovided, a locking pin engaging into a slotted guide which is formed ona sealing washer, and the sealing washer being composed of a hardenablesteel.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features of the invention result from the following descriptionand the drawings, in which exemplary embodiments of the invention areshown in a simplified manner and in which:

FIG. 1 a shows an internal combustion engine in a purely diagrammaticmanner,

FIG. 1 shows a longitudinal section through an apparatus according tothe invention,

FIG. 2 shows a plan view of the apparatus according to the inventionfrom FIG. 1, along the line II-II,

FIG. 3 shows a perspective view of a housing element of the apparatusaccording to the invention according to FIG. 1, and

FIG. 4 shows a plan view of the further apparatus according to theinvention, in an analogous manner to that from FIG. 1, along the lineII-II.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 a outlines an internal combustion engine 100, a piston 102 whichsits on a crankshaft 101 being indicated in a cylinder 103. In theembodiment shown, the crankshaft 101 is connected to an inlet camshaft106 and an outlet camshaft 107 via in each case one flexible drive 104and 105, respectively, it being possible for a first and a secondapparatus 1 to ensure a relative rotation between the crankshaft 101 andthe camshafts 106, 107. Cams 108, 109 of the camshafts 106, 107 actuatean inlet gas exchange valve 110 and the outlet gas exchange valve 111.There can likewise be provision to equip only one of the camshafts 106,107 with an apparatus 1, or to provide only one camshaft 106, 107 whichis provided with an apparatus 1.

FIGS. 1 and 2 show a first embodiment of an apparatus 1 for the variablesetting of the control times of gas exchange valves of an internalcombustion engine. In the following text, the invention will beexplained using an apparatus 1 which is driven by a belt. Apparatuseswhich are driven by chains or gearwheels are likewise conceivable. Thespecial feature of the apparatuses which are driven by belts lies intheir pressure-medium-tight encapsulation which is not necessary in theother embodiments. An adjusting apparatus 1 a essentially comprises astator 2 and an output element 3 which is arranged concentrically withrespect to the former. FIG. 2 shows a plan view of a sealing washer 12,components which lie behind the said sealing washer 12 being indicatedby dashed lines.

The output element 3 comprises a wheel hub 4, on the outer circumferenceof which axially extending vane slots 5 are formed, and five vanes 6which are arranged in the vane slots 5 and extend radially outwards.Furthermore, the output element 3 is provided with a stepped centralhole 4 a, into which a camshaft (not shown) engages in the mounted stateof the apparatus 1, from the right in FIG. 1. In the mounted state ofthe apparatus 1, the latter is connected fixedly in terms of rotation tothe camshaft, for example by means of a force-transmitting, frictional,form-fitting or material-to-material connection, or by means offastening means.

The stator 2 is configured as a thin-walled sheet-metal part, the lattercomprising inner circumferential walls 7 and outer circumferential walls8 which are connected to one another via side walls 9. The inner and theouter circumferential walls 7, 8 extend substantially in thecircumferential direction, whereas the side walls 9 extend substantiallyin the radial direction. The stator 2 is manufactured in one piece froma sheet-metal blank, by means of a forming process without cutting.Here, there can be provision to manufacture the stator 2 without cuttingby means of a deep-drawing method, for example from a steel sheet. Thestator 2 is mounted rotatably on the output element 3 via the innercircumferential walls 7 which bear against a cylindrical circumferentialwall of the output element 3. Starting from the inner circumferentialwalls 7, the side walls 9 extend substantially in the radial directionoutwards and merge into the outer circumferential walls 8. As a resultof this construction, a plurality of pressure spaces 10, five in theembodiment shown, are formed which, as described in the following text,are closed off in a pressure-tight manner in the axial direction by ahousing 11 or by a sealing washer 12.

The vanes 6 are arranged on the outer circumferential surface of theoutput element 3 in such a way that in each case one vane 6 extends intoa pressure space 10. Here, the vanes 6 bear in a pressure-tight manneragainst the outer circumferential walls 8 of the stator 2 in the radialdirection. For this purpose, spring elements 13 which displace the vanes6 radially outwards are arranged in the vane slots 5. The width of thevanes 6 is configured in such a way that the vanes 6 bear against thehousing 11 or the sealing washer 12 in the axial direction. As a result,it is achieved that each vane 6 divides a pressure space 10 into twopressure chambers 14, 15 which act against one another.

The stator 2 and the output element 3 are arranged within the housing 11which is configured in such a way that it encapsulates these componentsin an oil-tight manner. The housing 11 comprises a first housing element16 which is of substantially cup-shaped configuration and a disc-shapedsecond housing element 17. The connecting point of the housing elements16, 17 can be sealed by means of a sealing medium (not shown) or bymeans of sealing joining processes. In the embodiment shown, a weldedconnection 16 a is provided which runs in the circumferential direction.The first housing element 16 is arranged on that side of the apparatus 1which faces the camshaft. A flat section, which stands perpendicularlywith respect to the axial direction of the apparatus 1, of a cup-shapedsection of the first housing element 16, called the base 18 in thefollowing text, is positioned symmetrically with respect to therotational axis of the first housing element 16, a cylindrical section19 which extends in the axial direction being formed. The section 19serves firstly to accommodate the camshaft (not shown) or apressure-medium distributor. Secondly, the outer circumferential surfaceof the cylindrical section 19 can be used as a seat for a radial shaftseal 20 in the case of a belt-driven apparatus 1, which radial shaftseal 20 seals the apparatus 1 with respect to a cylinder head (notshown).

The internal diameter of the substantially cylindrical circumferentialsurface of the cup-shaped section of the first housing element 16 isadapted to the external diameter of the outer circumferential walls 8 ofthe stator 2. This ensures a centered accommodation of the stator 2 inthe first housing element 16. Furthermore, the substantially cylindricalcircumferential surface of the first housing element 16 is provided withformed recesses 21 which extend radially inwards between adjacent outercircumferential walls 8 of the stator 2. The formed recesses 21 areconfigured in such a way that they bear against the respective two sidewalls 9 of the stator 2 in the circumferential direction. As a result, aform-fitting connection is produced in the circumferential directionbetween the stator 2 and the housing 11, as a result of which the twocomponents are connected to one another fixedly in terms of rotation.Here, there can be provision for the formed recesses 21 to extend as faras the inner circumferential walls 7 of the stator 2, or for the formedrecesses 21 to engage only partly into this hollow space.

Furthermore, a radially extending collar 22, in which holes 23 areformed, is formed on that end of the first housing element 16 whichfaces away from the camshaft.

The second housing element 17 is arranged coaxially with respect to thefirst housing element 16, the outer circumferential surface of thesecond housing element 17 being configured in a complementary manner tothe collar 22 of the first housing element 16. The two housing elements16, 17 and a drive wheel 24 which is configured as a belt pulley areconnected to one another fixedly in terms of rotation by means ofconnecting means 24, screws in the exemplary embodiment shown. As analternative, force-transmitting or material-to-material connectingmethods can also be provided. In addition, the inner circumferentialsurface of the drive wheel 24 can be configured in a complementarymanner to the outer circumferential surface of the first housing element16, as a result of which the drive wheel 24 engages into the formedrecesses 21 of the first housing element 16 and the two components aretherefore connected in a form-fitting manner in the circumferentialdirection. The introduction of the torque which is transmitted from thecrankshaft to the drive wheel 24 can then be transmitted via theform-fitting connections between the drive wheel 24 and the formedrecesses 21 of the first housing element 16 and, furthermore, via theform-fitting connections between the formed recesses 21 and the stator 2to the latter. This form-fitting connection of the components in thecircumferential direction replaces the frictional connection which isdescribed in the prior art between the bases of the housing elements andan axial side face of the stator 2. The transmitted forces therefore actin the direction of the connection between the components and over aconsiderably greater surface area, as a result of which the forces canbe transmitted reliably. The transmitted force is distributed to agreater connecting surface area, as a result of which the stator 2 canbe configured with thinner walls. As a result, in addition to thefunctional safety of the torque transmission, the weight of theapparatus 1 and therefore its moment of inertia and also the costs arereduced.

As shown in FIG. 1, the second housing element 17 can be provided with acentral opening 17 a. In one embodiment of the apparatus 1, in which theoutput element 3 is fastened to the camshaft by means of a centralscrew, this opening 17 a serves as an engagement opening for a tool inorder to tighten the central screw. In this case, the opening 17 a canbe closed in an oil-tight manner by means of a cover (not shown) afterassembly of the apparatus 1 on the camshaft.

Embodiments of the apparatus 1 are likewise conceivable, in which thesecond housing element 17 is configured without an opening 17 a.

Shaped elements 11 a are formed on the second housing element 17, whichfirstly reinforce the component and secondly increase the surface areaof the housing 11 and therefore contribute to improved cooling. Anembodiment of the shaped elements 11 a as cooling fins is particularlyadvantageous.

FIG. 3 shows a perspective view of the first housing element 16. Theformed recesses 21 are clearly visible, which engage inwardly into thehollow spaces of the stator 2 in the radial direction. On the outercircumferential surface, the formed recesses 21 likewise make engagementof the drive wheel 24 possible, the inner circumferential surface of thedrive wheel 24 advantageously being adapted to the outer circumferentialsurface of the first housing element 16.

As can be seen in FIG. 1, the pressure spaces 10 are closed in apressure-tight manner in the axial direction on that side of theapparatus 1 which faces the camshaft by the base 18 of the first housingelement 16. For this purpose, the base 18 of the first housing element16 is of flat configuration and is arranged in such a way that itadjoins the output element 3 or the stator 2 directly in the axialdirection. A sealing washer 12 is arranged on that side of the apparatus1 which faces away from the camshaft between the second housing element17 and the stator 2 or the output element 3. The outer circumference ofthe sealing washer 12 is adapted to the inner contour of the firsthousing element 16, as a result of which the latter is connected fixedlyin terms of rotation to the housing 11 and therefore to the stator 2. Itbears both against the output element 3 and against the stator 2, atleast in the region of the pressure spaces, and is pressed against thestator 2 by means of the second housing element 17, as a result of whichthe pressure spaces 10 are closed in a pressure-tight manner in thisaxial direction. As an alternative, it is likewise conceivable to omitthis sealing washer 12 and to seal the pressure spaces 10 axially by wayof the second housing element 17. For this purpose, this second housingelement 17 would likewise have to be of flat configuration.

As a result of the fact that the base 18 of the first housing element 16is used as a sealing face for the pressure spaces 10 in the axialdirection, a second sealing washer can be omitted, as a result of whichthe number of components and therefore the assembly expenditure and thecosts of the apparatus 1 can be reduced. These advantages could beincreased by virtue of the fact that the sealing washer 12 is likewiseomitted and the pressure spaces are likewise sealed in this axialdirection by the second housing element 17.

Furthermore, the apparatus 1 is provided with two groups ofpressure-medium lines 25, 26 which, starting from the central hole 4 aof the output element 3, extend outwards in the radial direction. Here,the first pressure-medium lines 25 open into the first pressure chambers14, whereas the second pressure-medium lines 26 open into the secondpressure chambers 15. Pressure medium can be optionally fed to or guidedaway from the first or the second pressure chambers 14, 15 by means of apressure-medium distributor which is arranged in the central hole 4 a ofthe output element 3, or alternatively by means of a control valve, viathe pressure-medium lines 25, 26. A pressure gradient can therefore bebuilt up between the first and second pressure chambers 14, 15, as aresult of which the vanes 6 are displaced in the circumferentialdirection and the relative phase position of the output element 3 withrespect to the stator 2 can therefore optionally be set in a variablemanner or maintained. As a result of the adjustment of the phaseposition between the output element 3 which is connected fixedly interms of rotation to the camshaft and the stator 2 which isdrive-connected to the crankshaft, the phase position between thecrankshaft and the camshaft can be influenced in a targeted manner andthe control times of the gas exchange valves can therefore be influencedrelative to the position of the crankshaft.

Furthermore, FIG. 2 shows an apparatus 27 for restricting the angle ofrotation, which is realized by a pin 28 which is connected fixedly interms of rotation to the output element 3 and a cut-out 29 which isformed on the sealing washer 12. The pin 28 engages into the cut-out 29,the cut-out 29 extending in the circumferential direction in such a waythat the pin 28 comes to bear against a substantially radially extendingwall of the cut-out 29 in both extreme positions of the output element 3with respect to the stator 2. As a result, it is prevented that thevanes 6 dip into the transition region between the outer circumferentialwalls 8 and the side walls 9. This prevents the vanes 6 from jamming onthe radii which are formed there.

In the event of insufficient pressure-medium supply to the apparatus 1,for example during the starting phase of the internal combustion engineor during idling, the output element 3 is moved in an uncontrolledmanner relative to the stator 2 on account of the alternating torquesand drag torques which the camshaft exerts on the said output element 3.In a first phase, the drag torques of the camshaft displace the outputelement 3 relative to the stator 2 in the circumferential directionwhich lies opposite to the rotational direction of the stator 2, untilthis movement is stopped by the apparatus 27 for restricting the angleof rotation. Subsequently, the alternating torques which the camshaftexerts on the output element 3 lead to the output element 3 andtherefore the vanes 6 oscillating to and fro in the pressure spaces 10,until at least one of the pressure chambers 14, 15 is filled completelywith pressure medium. This leads to higher wear and to noise developmentin the apparatus 1. Furthermore, the phase position between the outputelement 3 and the stator 2 oscillates at a high amplitude in thisoperational phase, which leads to irregular operation of the internalcombustion engine. In order to prevent this, a locking device 30 isprovided in the apparatus 1. The said locking device 30 comprises alocking pin 31 which is arranged in a recess of the output element 3 andis displaced in the direction of the sealing washer 12 by means of aspring. A slotted guide 32 is formed on the sealing washer 12, intowhich slotted guide 32 the locking pin 31 is displaced in a maximumearly position or a maximum late position of the output element 3 withrespect to the stator 2. In this case, the locking pin 31 bears againstthe radial delimiting walls of the slotted guide 32, the said lockingpin 31 extending at the same time into the receptacle which is formed onthe output element 3. As a result, a form-fitting, mechanical connectionis produced between the output element 3 and the stator 2 in a relativephase position which corresponds to an optimum position for startingand/or idling of the internal combustion engine. In addition to thelocking of the output element 3 to the stator 2 in one of the maximumend positions, there can also be provision for both components to belocked relative to one another in a centre position. The sealing washer12 is advantageously configured from a hardenable steel. The sealingwasher 12 is subjected to a hardening process after being formed, as aresult of which it can absorb the forces which are transmitted via thelocking pin 31 in a functionally reliable way. This leads to anincreased service life of the apparatus 1.

Furthermore, means are provided, in order to displace the locking pin 31back into the receptacle when the apparatus 1 is supplied sufficientlywith pressure medium, and therefore to cancel the locking action. In theembodiment shown, there is provision for pressure medium to act on theslotted guide 32 via pressure-medium channels 33. The pressure-mediumchannels 33 are configured as grooves which are formed in the side faceof the output element 3 and extend from at least one of the pressurechambers 14, 15 as far as the slotted guide 32.

The pressure medium which is guided into the slotted guide 32 displacesthe locking pin 31 back into the receptacle counter to the force of thespring, as a result of which the fixed phase relationship between theoutput element 3 and the stator 2 is cancelled.

Here, there is provision for the pressure-medium channels 33 tocommunicate with the slotted guide 32 only in a defined small angularinterval of the phase position between the stator 2 and the outputelement 3.

The housing 11 is advantageously configured as a sheet-metal housing,the two housing elements 16, 17 being manufactured from a sheet-metalblank by means of in each case one forming process without cutting.Here, techniques such as deep-drawing processes are to be considered,for example. The reliable sealing action of the apparatus 1 is ensuredby the formation of the housing 11 from a steel-sheet blank, as a resultof which the apparatus 1 can be used as a belt-driven camshaft adjuster.Camshaft adjusters of this type are usually arranged outside thecylinder head, as a result of which reliable sealing of the apparatus 1becomes necessary. Leakage oil which occurs is collected by theformation of the housing 11 as a sheet-metal formed part within theapparatus 1, and can be returned into the cylinder head by channelswhich are formed on the cylindrical section 19. As an alternative, anannular gap can be formed between the section 19 and the camshaft, inorder to guide leakage oil back into the cylinder head. The firsthousing element 16 is advantageously sealed relative to the cylinderhead via a radial shaft seal 20 which is arranged on the section 19.

Expensive post-treatment for sealing the output element 3 which isnormally configured as a porous sintered component can be omitted as aresult of the encapsulation of the stator 2 and the output element 3within the housing 11. Any small leakage which occurs as a result of thesintered material or at the sealing locations is held within theapparatus 1 by the housing 11 and can be returned into the cylinderhead.

In the embodiment in which the pressure spaces 10 are closed in apressure-tight manner by means of a sealing washer 12 on that side ofthe apparatus 1 which faces away from the camshaft, this sealing washer12 can at the same time serve as a compensation washer, in order tocompensate for any tolerances which occur of the two housing elements16, 17.

FIG. 4 shows a further embodiment of an apparatus 1 according to theinvention. In this illustration, the sealing washer 12 has been removed.This embodiment is largely identical to the first embodiment, for whichreason identical components have been provided with identical referencenumerals. In contrast to the first embodiment, the stator 2 a is notconfigured here as a thin-walled sheet-metal formed part, but as a solidcomponent. Here, this can be, for example, a stator 2 a made from asintered material. In this embodiment, the housing 11 fulfils the samefunctions as in the first embodiment (torque transmission, sealing ofthe pressure spaces 10), as a result of which the same advantages areattained. The formed recesses 21 engage into indentations 21 a which areformed on the stator 2 a. These indentations can be formed on thesintered component without additional costs by virtue of them alreadybeing taken into consideration in the forming die.

LIST OF REFERENCE NUMERALS

-   1 Apparatus-   1 a Adjusting apparatus-   2 Stator-   2 a Stator-   3 Output element-   4 Wheel hub-   4 a Central hole-   5 Vane slot-   6 Vane-   7 Inner circumferential wall-   8 Outer circumferential wall-   9 Side wall-   10 Pressure space-   11 Housing-   11 a Shaped element-   12 Sealing washer-   13 Spring element-   14 First pressure chamber-   15 Second pressure chamber-   16 First housing element-   16 a Welded connection-   17 Second housing element-   17 a Opening-   18 Base-   19 Section-   20 Radial shaft seal-   21 Formed recesses-   22 Collar-   23 Holes-   24 Drive wheel-   25 First pressure-medium line-   26 Second pressure-medium line-   27 Apparatus for restricting the angle of rotation-   28 Pin-   29 Cut-out-   30 Locking device-   31 Locking pin-   32 Slotted guide-   33 Pressure-medium channel-   100 Internal combustion engine-   101 Crankshaft-   102 Piston-   103 Cylinder-   104 Flexible drive-   105 Flexible drive-   106 Inlet camshaft-   107 Outlet camshaft-   108 Cam-   109 Cam-   110 Inlet gas exchange valve-   111 Outlet gas exchange valve

1. Apparatus for the variable setting of the control times of gasexchange valves of an internal combustion engine, comprising: a statorand an output element which is arranged coaxially with respect to thestator, the stator and the output element being mounted such that theycan rotate with respect to one another, a housing which is configuredseparately with respect to the stator and with respect to the outputelement and which surrounds the stator and the output element at leastpartly, wherein an outer circumferential surface of the stator isconfigured in the circumferential direction with a radial profile, intowhich the housing protrudes in such a way that a form-fitting connectionof both components is produced in the circumferential direction. 2.Apparatus according to claim 1, the housing prevents pressure mediumfrom escaping from the apparatus.
 3. Apparatus according to claim 1,wherein at least one pressure space is formed between the stator and theoutput element, the housing comprises at least two housing elements, andat least one flat section of the housing which stands perpendicularlywith respect to the axial direction of the apparatus acts as a sealingface for the pressure space in the axial direction.
 4. Apparatusaccording to claim 1, wherein the stator is configured as a sheet-metalpart which is formed without cutting.
 5. Apparatus according to claim 4,wherein the stator is manufactured by a deep-drawing process. 6.Apparatus according to claim 3, wherein at least one of the housingelements configured as a sheet-metal part which is formed withoutcutting.
 7. Apparatus according to claim 6, wherein at least one housingelement is manufactured by a deep-drawing process.
 8. Apparatusaccording to claim 1, wherein the two housing elements are connected toone another by means of a welded connection.
 9. Apparatus according toclaim 1, wherein a cylindrical section which extends in the axialdirection is formed on the housing for sealing off the apparatus withrespect to a radial shaft sealing ring.
 10. Apparatus according to claim9, wherein a camshaft engages into the section, and in that a gap isformed between the internal diameter of the section and the camshaft.11. Apparatus according to claim 1, wherein shaped elements are formedon at least one of the housing elements in order to increase the surfacearea.
 12. Apparatus according to claim 1, wherein a locking device isprovided, a locking pin engaging into a slotted guide which is formed ona sealing washer, and the sealing washer being composed of a hardenablesteel.